1. Field of the Invention
The present invention concerns a method and a magnetic resonance system in order to acquire MR data with diffusion information in a volume segment of an examination subject.
2. Description of the Prior Art
In order to generate a diffusion contrast in MR images, various gradient switching schemes have been developed.
“Spin Diffusion Measurements: Spin Echoes in the Presence of a Time-Dependent Filed Gradient”, E. Stejskal, J. Tanner, The Journal of Chemical Physics, Vol. 42, Nr. 1, 1965, Pages 288-292 describes such a method in which the spin echo condition is satisfied at the point in time of the acquisition of the k-space center and a defined wait time is to be maintained before and after the RF refocusing pulse.
“Evaluation of a Modified Stejskal-Tanner Diffusion Encoding Scheme, Permitting a Marked Reduction in TE, in Diffusion-Weighted Imaging of Stroke Patients at 3 T”, J. Morelli et al., Investigative Radiology, Vol. 45, Nr. 1, 2010, Pages 29-35, likewise discloses a method in which the spin echo condition is satisfied at the point in time of the acquisition of the k-space center, with a non-variable diffusion time, wherein a parameter range of measurement protocols is limited to cases which are compatible with a diffusion coding before and after the refocusing pulse.
“Echoplanar Diffusion Tensor Imaging of the Lower Leg Musculature Using Eddy Current Nulled Stimulated Echo Preparation”, G. Steidle, F. Schick, Magnetic Resonance in Medicine 55, 2006, Pages 541-548, describes a method in which a stimulated echo condition is satisfied at the point in time of the acquisition of the k-space center and a defined wait time is to be maintained before and after the RF store/restore pulse.
“Eddy Current-Nulled Diffusion Weighting”, O. Heid, Proc. Intl. Soc. Mag. Reson. Med. 8, 2000, Page 799, describes such a method in which a double spin echo condition is satisfied at the point in time of the acquisition of the k-space center, with a non-variable diffusion time, wherein a parameter range of measurement protocols is limited to cases in which four gradient pulses with identical amplitude and identical ramp durations are used.
“Bipolar Diffusion Encoding with Implicit Spoiling of Undesired Coherence Pathways”, T. Feiweier, Proc. Intl. Soc. Mag. Reson. Med. 19, 2011, Page 178, likewise describes a method with a non-variable diffusion time, wherein a parameter range of measurement protocols is limited to cases in which four gradient pulses with identical amplitude and identical ramp durations are used.
However, these methods according to the prior art have specific disadvantages. There are either limitations with regard to the minimum realizable echo time, or the establishments of a coding time δ and a diffusion time Δ are inflexible, or a parameter range of measurement protocols with which the resolution and the field of view are determined (and which leads to a valid chronological workflow) is very limited.